Reading device for characters represented on a plate in micro-reproduction



T. KRNER ETAL READING DEVICE FoR CHARACTERS REPRESENTED oN Nov. 25, 1958 A PLATE :EN MICRO-REPRODUCTION 6 Sheets-Sheet 1 Filed Feb. 9, 1955 lllr .flu

Nov. 25, 1958 r KRNER ErAL 2,861,499

READING DEVICE .FOR CHARACTERS REPRESENTED ON A PLATE IN MICRO-REPRODUCTIONv Filed Feb. 9, 1955 6 Sheets-Sheet 2 Nov. 25, 1958 r. KRNER ErAL 2,861,499

READING DEVICE FOR CHARACTERS REPRESENTED ON A PLATE IN MICRO-REPRODUCTION Filed Feb. 9. 1955 6 Sheets-Sheet 3 17 T' a7 37/ g If e u l I ##36 'C. d5 i Uli 2S p i Il l a l1 i E a7 .a1 22 e/ Nov. 25, 1958 KRNER HAL T. 2,861,499 READING DEVICE FCR CHARACTERS REPRESENTED oN A PLATE 1N MICRO-REPRODUCTION Filed Feb. 9. 1955 6 Sheets-Sheet 4 Fig. l2

*Il Il Il Il Il Il lll .r Il Il Il l 'Il lill Il Il Il Il Il 11:11 Il Il Il Il Ill-II Nov. 25, 1958 T. KRNER ETAL 2,861,499 READING DEVICE FOR CHARACTERS REPRESENTED ON A PLATE IN MICRO-REPRODUCTION Filed Feb. 9, 1955 6 Sheets-Sheet 5 Nov. 25, 1958 T. KRNER ET AL READING DEVICE FCR CHARACTERS REPRESENTED oN A PLATE 1N MICRO-REPRODUCTION 6 Sheets-Sheet 6 Filed Feb. 9L 1955 ing anges on the runner.

United States Patent ce READNG DEVICE FOR CHARACTERS REPRE- SENgED N A PLATE IN MICRO-REPRODUC- TIO Theodor Krner, Starnberg, and Wilhelm Friedrich Pohl, Schwabisch Gmund, Germany Application February 9, 1955, Serial No. 487,024 i Claims priority, application Germanyy May 21, 1954 11 Claims. (Cl. 88-39) practice by micro-reproduction which in general is made readable by magnifying it with a projector. This, however, requires in any case the use of an additional comparatively voluminous apparatus.

To obviate these disadvantages we have developed a reading device which makes looking up in reference.

works or the like quick and easy and possible with one hand only. Our reading device may be manufactured with any desired dimensions from pocket size upto the dimensions of a desk plate. The invention utilizes the known micro-reproduction of characters on a plate which can be read by means of a reading device. According to the invention elongated track means, preferably in the form of a U-shaped yoke or track member serving to guide the reading lens system in front of the plate and extending over both sides of the plate is designed as a sliding track upon which a lens carrier or a runner together with the lens system can be placed. The elongated track means have a pair of guide portions'and at least one connecting portion connecting the guide portions and when the device is mounted on the plate the guide portions will respectively extend parallel to and at least partly over opposite faces of the plate with the connecting portion straddling one edge of the plate.` The yoke member is provided with guides such as guiding.

slots at grooves for the runner. The guide means are preferably provided on both lateral facesof the yoke member and are preferably formed in such a manner as to permit sliding engagement with guiding pins or guid- The runner is provided with extensions such as small leaf springs which serve to hold it at a fixed distance from the sliding track in its position of rest without being limited thereby to be moved in lateral direction. Instead of a rigid sliding track also extensible resilient holding strings may be provided sur-t rounding both faces of the plate and enabling the runner to be shifted together with the lens system over both faces of the plate. For this purpose the runner may have eyes, holes or the like in which the holding strings are guided. In order to be able to move the lens system also over larger areas for which the extensibility' of the strings is not sufficient, sliders may be provided which are slidable on the edges and-embrace them and which have holes or eyes for the holding strings.

The cooperative-connection of the lens system with 2,861,499 Patented Nov. 25, 1958 the sliding track may be also in the form of a magnetic coupling by using permanent magnets for the lens runner or for the sliding track or for both. If desired, one or a plurality of magnetizable or non-magnetizable intermediate members may be arranged between the lens runner andthe sliding track which intermediate members, if being magnetizable, likewise may be made permanent magnets. To prevent lateral sliding off of the lens runner, guiding grooves or profiled guiding rails may be provided on the sliding track which are capable of being engaged by projections or flanges on the lens runner.

The micro-reproduction may either be applied on both faces of a plate in general by a photochemical procedure or the micro-reproduction may be on foils which are subsequently applied to both faces of the plate.

The plates may have a circular or a polygonal, preferably, however, a circular or a rectangular configuration.

If circular plates are used they are rotatable about 'an axis. For this purpose the plates may be provided with a hole so as to be rotatable about a pivot. In order to be able to exchange the plates in a quick and `ample manner the pivot is secured by a screw which can easily be loosened. Screw and pivot constitute clamping means to clamp the plate together. A particularly simple arrangement is obtained if the same pivot is used to hold the two legs of the yoke member. Under certain circumstances it may be convenient to provide on the pivot of the plate an automatically rotatable winding up spring and in addition to provide on the yoke member brake means for the rotating plate. The edge of the plate may be knurled to obtain a better grip if the plate is to be manually rotated or braked.

Similarly as with the embodiment using a circular plate the micro-reproduction may be placed between two rectangular plates the edges of which are embraced at least at two edges by preferably detachable clamps in particular by frame members acting as clamps clamping means of which one is connected with guiding means for a slider to which the U-shaped yoke member is attached. The clamps or frame may be secured to two opposite edges of the plates but may be arranged also on three adjacent edges of the plate in particular in such a manner that a continuous frame acting as a clamp embraces the plates at three edges at least partially. This frame may be U-shaped both as to its general configuration and in its cross-section. At the clamps or frame the plates may -be held together by screws, rivets, clips with or without springs or the like. Thus the guiding rail may be designed as a springy hollow bar the entrance ends of which are haring to facilitate the insertion of the plates. In order to hold together such portions of the plates which are opposite the frame, pressure members may be provided on the yoke member embracing the plates and serving as a sliding track which pressure members may be secured adjacent the arcuate portion of the yoke member and be provided with springs or not and are acting to urge the plates towards one another. l

The lens system of the device may comprise depending upon the magnification desired ordinary lenses, aplanatic lenses or wide angle lenses. For a higher magni-cation power microscopes can be used. The arrangement may be made such that lenses and microscopes of different magnifying powers are easily interchangeable. Thus an internally cylindrical or conical shaft may be provided on the runner to permit the lenses or microscopes to be easily insertable or removed. The shaft may visual fieldr it may be desirable to ind out` prior to read-V ing the approximate reading place on the plate carrying the micro-reproduction. For this purpose a reading lens.

or less magnifying power may be utilized which can be slipped on the shaft of the lens or microscope with which the reading device is used by:meansof1a1suitable1clamp: 5

spring. To find out the desiredrreading tieldlquicklylthe; reading lens may be turned around thefsha-ftt Another;

possibility of attac-hingthe readinglenseconsistsiniatet taching it by means Vof. a clamping yokeftothe- U-shapedr:

yoke member servingas a sliding trackin such a-rnannert as to be slidable thereon.

The micro-reproductions for vthe two'reading faces are separated fromI each other by anI intermediate space'.l This intermediate space is occupied by a plate which.'y may either beopaque if itconsists` of `armetal or'of.

another opaquevmaterial. The :plate may be, however, also translucent` so as toV constitute between the microreproductions on' bothv faces` a translucent intermediate 1.

layer. The characters being represented in micro-repro-y duction onboth faces of the plate thus have a certain distance-from eachother which,` however; in most cases-i If the microgram carrier",

will not be very important. is very thin, andclear-ly transparentiit-.might happen that notwithstanding zsharp-adjustment ofthe focal `point of'. the reading llensreadingis impaired bythe microgram.'

on` the oppositeface. This is the reason why a =thin microgram carrier should Aeither be opaque so that a-l microgramlis observed with impinging light or it Should only be translucent such as a focussing screen so' that the microgram applied on the other facerdoesV not impair:v

reading.V

There is still'the possibilityto use a clearly transparent;

microgram carrier if 'it is thick'enough that upon obser. vation'oftheg-one face of the plate bythe lens the opposite face carrying another micro-reproduction'appears` blurred or out ofA focus.

These and other features of the-invention willappear.v`

more fully from-the following detailed descriptionzof several embodiments thereof in connection with the ac-A companyingdrawings, givenmerely .by way of' .example` and in-which:

Fig. 1 ris a plan vfview ofy the device according .to the" inventioninwhich the circular plate is` used;

Fig. Zlis asectional'elevational view of the device showing. the location offthe yoke member;

Fig. 3fis-a sectionaL-view taken on the line A-Bl of z Fig. 2;

Fig.-4 isa planviewf of" another embodiment of the invention showingwith `full lines a circular/plate 'and' with dotted lines a-rectangular plate and a possibility of. attaching a microscope,ythis llatter being illustrated in' with av U-shaped frame .encompassing-the:platekonthreef edges;

Fig; 8 isasectional view taken..on;thelineC.-D of Fig. 7:

Fig. 9 is a plan viewr of la plate .showing twoirame members attached to opposite sides of the plate;

Fig. 10 showsV in diagrammatic manner a view-finder lens attached to the tube of the rea-ding'lens,"v

Fig. 11 shows in whichmannertheyiew finderllensy may be shiftably attached to the U-shaped yoke member;Y

Fig. 12 shows a springy lateral framezused'for hold-4 ing the plates with one. embodimentand..

Fig-,13 anotherembodiment of thearrangement shownf in Fig. 12;

Fig. 14 shows a magnetic connectionbetweenf lensrl runner and sliding track and Fig.Y 15 another magnet* connection :.between-lensfrun ner: and sliding track .in section :through 'aipair vvoiguidb 75 4 ing pins, the plane of section being normal to the sliding track;

Fig. 16 shows the use of yresilient holding strings instead of a rigid sliding track in their position of rest and Fig. 17 a similar view,- however with the strings being extended for reading on a place of the plate which cannoti-beereachedH in the position of rest of the string;

Fig; 18 shows a slider attached to the edge of '.1 plate and provided with notches for guiding the resilient strings;

Fig.l 19a corresponding slider, however with holes in stead of notches;-

Fig.l 20shows in'whichway the U-shaped slider embraces the edge of the plate;

Figzllf'isasectional 'view and shows the arrangement of the resilient strings of Fig. 16 drawn to an enlarged scale, the section being taken along line E-F of Fig. 16;

Fig. 22 showsa runner cooperating with resilient strings andv provided with eyes rand' Fig. 23 a runner provided with holes through which thefresilientl stringsV are passed;

Figi 24-lshows the arrangement of a condenser to improve theillumination of the micro-reproduction to be readoi.

One-embodiment of the'present invention shown in' Figs. 1-3Ycomprises .a circular plate 1 on both faces of which the complete contents of dictionaries, timetables, map vlettering or other records are projected, printed or applied in a photogrammetric manner. In this way it is possible, for instance, to accommodate on one face of a plate lhaving al diameter of aboutl four inches 16,000 catchwordslof-'apocket dictionary of the height of letters `is approximately 6.3 mil,' while on the reverse side of the plate further 16,000 words-may be placed. The materialcarrying the micro-reproduction may also be provided on a foiltor on-atilm which is placed between two plates.

A." pivotpin" Zfextends'through the center of plate'l about which pivot the plate may `be rotated. Pin 2 has pivoted thereto a U-shaped track member 3 simultaneously'servingas a sliding track for a lens. The U- shaped track member 37overlies with its legs or guide` portions 3 both faces of thel plate 1 and the guide portions 3 are connected by a connecting portion 3 which straddles `the edge of thel plate 1. A runner 4 carrying a lens 5`is slidably attachedto the yoke member 3 so as lto be movable from the axis of the plate 1 up to its edge and vice versa in a similar manner as the runner of-aslide rule.l For this purpose both lateral faces of the yoke member 3 are provided each with a guiding slot or'guiding groove within which a guide projection 7 of the runner 4 is slidably engaged. The connection between runner 4'and yoke member 3 is such as not to hinder the sliding motion of the runner when changingr from one-side'toI the other over the edge 8 of the plate.V

reading by :means'of the lens, the runner is provided at itslends with a small U-shaped extension 9 at each endv inslidableengagementwithfa ange'lOfofthe yoke mem-v ber -3 whereby therunner 4 :is safely held on its slidingtrack.. At each side of the yoke member 3 at the locationffrom which the'runner 4 isJ moved with its leadingend'from the edgelofv the plate towards the center of the plate, the flanges 10 of the yoke member are shortened by the length ofthe runner 4.?Y

To-'fac'ilitate handlingfof fthe device the edge 8, of the plate 1 is 'knurlecL To prevent themicro-reproduction on the plate 1 from being marredit is either-provided with a resistant coat ofV lacquer or coveredbyltwo Plexiglas plates 11.

In;v modilicationI of :the constructiony shown thereading deviccfnray als'oibe provided=on the pivot pin 2 with a winding-up springe and a-'- braking mechanism (not shown) so that during the use of the device the plate 1 is automatically rotated. should be provided on the yoke member 3 to permit stopping the rotation of the plate in any desired location.

Figs. 4 to 6 show another embodiment of the invention with which a microscope is used. Both a circular plate 1 and a rectangular plate 12 can be used as shown. Y The circular plate 1 kcarries a pivot pin 2 on which similar to the embodment shown in Figs. 1 to 3 a yoke member 3 serving as a sliding track is mounted so as to extend over both faces of the plate. The yoke member 3 has slidably attached thereto by means of holding eyes 13 an internally cylindrical or conical shaft 14 into the cylindrical -or conical opening of which the shaft 15 of the' microscope is inserta'ble. The arrangement may be made such that microscopes of different type and magnifying power or lenses can easily be interchanged. If desired, the yoke member can be made of a springy material so that the objective cone of the microscope is urged with light pressure towards the text-bearing plate in order to give the objective cone the necessary fixed location.

The adjustment of the text-bearing plate to the desired point of observation is effected with the embodiment having a circular plate 1 as described by rotating the sliding track about the pivot 2. With the embodiment having a rectangular plate 12 the yoke member is displaced parallel to one edge of the plate as shown hereinafter in detail by way of example.

When using a rectangular plate a microgram carrier 16 is held between two transparent plates 12 of glass or plastics (Fig. 8). The microgram carrier has applied to its both faces e. g. by pasting or photographically the micrograms to be read. As already noted the microgram carrier should either be opaque or translucent such as a focussing screen or, if clearly transparent, it should be thick enough that as regards the focal length of the lense the observation of the microgram on one face of carrier is not impaired by the microgram on its other face.

The plates 12 are embraced at three edges by legs 17 and 18 of a frame member or clamping means not only U-shaped in cross section but also in its general configuration (Figs. 7e8). 19 and 20 denote the parallel legs of the U-shaped frame as such. The likewise parallel legs 17 and 1S of the U cross section are at a distance from each other to permit the insertion of the plates 12 holding the microgram carrier 16 between them such that the plates 12 remain at the desired location without, however, rendering the insertion of the plates into the frame difficult. The legs 19 and 20 of the frame member may be made longer or shorter, as desired, or may be so dimensioned that they extend throughout the entire length of the edges. On the other hand it is not necessary that the legs 17 and 18 of the frame member cover the entire length of the edge. It would be sufficient if they have the same length as the legs 19 and 20 measured from the two corners.

The U-shaped frame member completed by the legs 17 and 18 is connected by means of a web 21 to guide means in form of a round bar 22 embraced by a guiding nut 23 by more than 180. The guiding nut 23 is provided at both of its ends with longitudinal slots 24 assuring a firm however springy guidance of the guiding nut 23 on the round bar 22. The guiding nut 23 further has secured thereto a sliding track 25 designed in the manner described. The reading lens 26 may be directed in the manner likewise described in the foregoing to both faces of the microgram carrier 16 by sliding the lens on the U-shaped yoke member 25.

As the plates 12 are not held by the frame member at their edges opposite the frame member they might have the tendency to separate each other. To prevent this two pressure members 27 are provided the distance between which is equal to the distance between the outer faces of the .plates 12. The pressure members 27 are In lthis case a control button secured to the U-shaped sliding track adjacent its arcuate portion 28.

The inward projection of the pressure members 27 i. e. the distance between them, may be rendered variable by means known as such, e. g. if a film placed between the plates 12 is to be moved for observation, becausel in this case the pressure between the two plates 12 must not be as high as when observingl a stationarily inserted microgram. Alternately also a small recess 29 may be provided in one plate which recess extends throughout the length of the plate and is so dimensioned as to permit the film to be inserted and drawn through.

ASince the visual field of an ordinary aplanatic lens 1s comparatively small it may be replaced by a wide angle lens such as a binocular lens. In case such lenses are not sufficient to permit rapidly looking up the region of the microgram to be observed, View finding lens 30 with less magnifying power and a larger visual field lmay be. employed which is clamped by means of a correspondingly shaped spring onto the shaft 32 of the lens 26. This permits the lens 30 to be rotated about this shaft whereby looking up is greatly facilitated.

In modification o f theV above the view finding lens 30 may be attached by means of an intermediate web 33 to a spring yoke 34 (Fig. 1l) slidably displaceable on the sliding track 25. VIf the View finding lens 30 is not necessitated it may be removed from the shaft 32 (Fig. 10) or from the slidingptrack 25 in ,a simple manner.

l The lenses may be provided with eyepiece cups and be made adjustable for focusing. Y

The U-shaped frame member shown in Fig. 7 may be replaced by two clamp-type ledges 35 and 36 secured in oppcsition to two edges of the rectangular plate (Fig. 9).

In case of need these ledges may be fastened to the plates 12 by means of screws, clamps, rivets or the like 37. A guide means in form of a guiding bar 38 for the slider is provided on one of the two ledges.

Our novel device permits of quickly and simply interchanging of micrograms of all kinds in the reading device. kFor exchanging a micro-gram by another first the guiding nut 23 togethervwith the elongated track means in the form of the U-shaped track member 25 is removed from the round bar 22. The U-shaped track member 25 has similar as the member 3, a pair of guide lportions or leg portions 25 located respectively on opposite sides of the plate and a connecting portion 25 straddling one edge thereof. Then the plates 12 are withdrawn from the frame together with the micrograms held between them whereupon the micrograms are removed from between them and replaced by new ones. This having been done the plates are again inserted together with the micrograms into the .frame member and then the guiding nut 23 is again slipped onto the round bar 22 whereupon the device is again ready for reading.

The cross sections of two frame members which have probed to be particularly useful in practice are shown in Figs. 12 and 13. Fig. ll2 shows a frame member comprising two opposite springy legs 39 which can be formed simply by bending a metal bar. The free ends of the legs are bent so as to be flaring. After the plates 12 holding the microgram carrier between them are removed from this frame the two legs 39 more or less approach each other under the action of their own elasticity. The flaring configuration of the two free ends facilitates the insertion of the plates. The guide nut 23 is slidably mounted in the manner described hereinbefore on the inner portion 40 of the frame of approximately circular cross section.

While the embodiment shown in Fig. l2 is characterized by an increased stability it involves, however, a

provided with a throat 42 limiting the movement of in- -sertion of the plates 12. The free legs 41 also in this case are biased towards one another so that they ap focussed to'anrobject in order to permit the focal pointof'the reading lensv 26 to be exactly-adjusted to the microreproduction.v These contradictoryrequirements may be metwithby arspringrsuch as a'leaf` spring provided within the lens runnen Anothery possibilityconsists in providing ar magnetic connection between the -lens runner and the sliding track. For this purpose either the lensrunner 44 or the'sliding trac-k245 or bothmay vbe made permanent magnets. If only one of these two elementsv isapermanent magnet the other must be offa magnetizable material. The lens'runner may be displace'cLalongl` the sliding track without this movement being hinderedby themagnetic` attraction and is held firmly and-without clearancefonfthe sliding track which permits a very exact adjustment'of the focal point to the microgram. To prevent the lens runner from being lost or from being laterally displaced also in this case laterally embracing anges 46 are provided engaging with corresponding slide bars or projections 47 ofthe -sliding track.

Instead of usingpermanent magnetic material for thelens runner or for the sliding track'it is also possible, if

the sliding track is magnetizable, yto provide on the lens runner magnetizable or permanent magnetic intermediate members 48; e. g. in recesses49 of the lens runner (Fig. 1.5). TheseY intermediate members 48 are guided in grooves 50 of the sliding track-51.-

If the lens runner or the sliding trackis magnetizable and one of these two elements is a permanent' magnet,-,the

intermediate members 48 need not be magnetizable or beVv permanentmagnets. l This arrangement assures not'only a safe adjustment ofthe'focalpoint of the lens to thel 40` runner 52 on the sliding tracklwithout it being necessary v microgram butalso Vproper lateral guidanceofthe lens be convenient even'when intermediate pieces areused to provlde lateral guiding anges and projections such i as 46 and 47, as shown in Fig. 14.

Ai very simple and inexpensive holdingand guiding devlce for the lensis' illustratedin Figs. 16 to 23. In this embodiment extensible resilient holding and guiding f strings 53 which form elongated track means are substituted for the previously described rigid yoke-shaped sliding track. These holding or-guiding strings haveY attached thereto the lensfor the microscope 54 in such a manner that itcan berlaterally displaced. To this end the` lens isvinserted into-a lens runner 55 which is'pro# vided eithergwith eyes 56 or with holes 56 throughwhich the resilient guidingfstrings. extend.

This arrangements permits to displace the lens inithe direction of the resilient guiding strings from one edge of the plate 57 to its other edge.

For displacing the lens-'transversely to the direction of theguiding strings 53 it will be suiiicient to exert a lateral `pressure on thelens Vrunner 55 for displacing the lens up to the desired point. Owing to the elasticity of the guiding strings 53 'the lens may -be directed to any point of the reading eld.

The holding strings may be arranged to extend over the plate 57 either in its longitudinal direction or in its transverse direction. Atv the same time the holding strings areurgingthe lens runner 55 towards the plate 57 so thatV the lens has always Vthe same invariable working distance from the micro-reproduction.

TheV guiding strings can bey secured Atothe -onefedgefof in Figs. l0 and. -ll for the Yview finding lens.

ate portion fof' the `clamping yoke- 66, formed of two substantially parallel leg portions 68 and a curved contheplate bymeanswoff knots Aor thelike in holes 58,`I

while at the-opposite edge of the plate 57 they aref guided in two notches or-recesses- 59'in such a manner` thattheyk will not. be ldisplaced laterally. For bringmg the'lensf54to the-other' face of.the plate 57 it Awill do to lift the guiding strings 53 by means of the lens runner 55 out Vof` their recesses 59'and toA shift thelens runner 55 to the :other face.

Instead of providing recesses 59 of invariable location,.U-shaped-slidersl60may be used which embrace oftwo oppositeedgesofthe plates 57 or on both opposite edges in such a manner thatV for' observing any placefon the plate onlya slight. resilient elongation of the guiding.: strings 53 isnecessar-yforno elongation at all sothan the lens 54 maybe immobilized at any desired loca-- tion .withoutbeingcompelled to hold it.

The elastic guidi.ng.stringsl may` be of any suitable elastic material. such .as Vrubber cords,` rubber bands,

stringsofpla'stic, covered= or uncovered spiral springs-- or thelike.`

Also withV this embodimentv an intermediate plate 16 may be providedY between fthe two protecting covering plates 12 consisting e.V gfofPlexiglas as shown f. i. in

Fig. 24. This intermediate. plate-may be as mentioned hereinabove of an opaqueY or a-translucent material or, if ofsufficientthickness, of a transparent material.

TheV magnificationV of `the micro-reproduction on ob-VV servationby means ofwa lensin particular onV observation by'meansofvafmricroscope the` light intensity of theobservedspace is reduced; This implies the possibility that, iffthe illumination of thesurroundings is poor,'themicro-reproductionbecomes illegible. yThis can be avoided usinga condenserV lens arranged opposite the reading lens or Amicroscope at the other face of the plates if these plates are translucent or transparent asf shown inFig. 24.v The embodiment of Fig. 24 shows a condenser lens 64 mounted-in a tube or the like 65 secured to a. clamping yoke 66 the other end of which canwbe clamped in a similar way to-the shaft 32 of thelens or to the tube 15 of the microscope such as shownl The arcunectingportion .67, hasA been placed far enough out wardly to permit` the-condenser together with the lens` Ytowbe moved over Ythe entirefsurface of the plate 12.

This arrangement. assures thatthe condenser is in anyA position of rest `oppositethe lens or the microscope and always .lights up the corresponding visual field of the microscope even when. the condenser is directed towards =a comparatively poor source oflight. clamping yoke' may. begiven a slight elastic `bias so that the base of the condenser is always slightly urgedH against the ksliding tracktZS in order toprevent rundesired movement of. the-condenser lens and accordingly variations. of the illumination of the'visual eld.

saidv guide portions,vsaid-track means adapted to lbeV mounted .onf the plate with-said guide portions respectively extendingV substantially parallel to and at least partly over opposite faces of theplate and said connect-VV ing portiontstraddling one edge of thefplate'when said track means aremounted on the plate; a len carrier slidably mounted on said elongated track means for sliding movement alongfsaidz-guide portions and said conf necting .portion thereof; t and lens meansA mountedton ysaid lens carrier-,1; .wherel-.ysaidV lens carrier .maybe movedf:

9 along said track means from one face of the plate to the other face thereof so that micro reproductions on either side of the plate may be read through said lens means.

2. A reading device for reading micro reproductions located on opposite faces of a plate comprising in combination, clamping means adapted to be mounted on the plate; elongated track means having a pair of guide portions and at least one connecting portion connecting said guide portions, `Said trackl means mounted on said clamping means with said guide portions respectively extending substantially parallel to and at least partly over opposite faces of plate and said connecting portion straddling one edge of the plate when said clamp-v ing means are mounted on the plate; a lens carrier slidably mounted on said elongated track means for sliding movement along said guide portions and said connecting portion thereof; Vand lens means mounted on said lens carrier, whereby `said lens carrier may be moved along said track means from one face of the plate to the other face thereof so that micro reproductions on either side of the plate may -be read through said lens means.

3. A reading device for reading micro reproductions located on opposite faces of a plate comprising, in combination, elongated clamping means adapted to be mounted on the plate extending along one side edge thereof; guide means on said clamping means; elongated track means having a pair of guide portions and at least one connecting portion connecting said guide portions, said track means mounted on said clamping means with said guide portions respectively extending substantially parallel to and at least partly over opposite faces of the plate and said connecting portion straddling one edge of the plate when said clamping means are mounted on the plate, said track means being operatively connected to said guide means for guiding said guide portions respectively over the opposite faces of the plate; a lens carrier slidably mounted on said elongated track means for sliding movement along said guide portions and said connecting portion thereof; and lens means mounted on said lens carrier, whereby said lens carrier may be moved along said track means from one face of the plate to the other face thereof so that micro reproductions on either side of the plate may be read through said lens means.

4. A reading device for reading micro reproductions located on opposite faces of a plate comprising, in combination, clamping means adapted to be mounted on the plate; a U-shaped track member having a pair of leg portions and a connecting portion connecting said leg portions, said leg portions being at the free ends thereof operatively connected to said clamping means for movement of said leg portions respectively over opposite faces of said plate with said connecting portion straddling one edge of the plate when said clamping means are mounted on the plate; a lens carrier slidably mounted on said U-shaped track member for sliding movement along said leg portions and said connecting portion thereof; and lens means mounted on said lens carrier, whereby said lens carrier may be moved along said U-shaped track member from one face of the plate to the other face thereof so that micro reproductions on either side of the plate may be read through said lens means.

5. A reading device for reading micro reproductions comprising, in combination, ,a plate assembly having a center plate and a pair of cover plates respectively extending over oppositey surfaces ofsaid center plate, at least said cover plates being made from transparent material, said plate assembly adapted to carry micro reproductions sandwiched between said center plate Aand said cover plates; clamping means for clamping said plates together; elongated track means having a pair of guide portions and at least one connecting portion connecting said guide portions, said track means movably mounted on said clamping means for movement of said l@ guide portions substantially parallel to and over the outer planar surfaces of said cover plates, respectively, with said connecting portion straddling one edge of said plate assembly; a lens carrier slidably mounted on said elongated track means for sliding movement along said guide portions and said connecting portions thereof; and lens means mounted on said lens carrier and facing one of Said cover plates, whereby said lens carrier-and said lens means mounted thereon may be moved along said track means from a position where said lens means faces said one cover plate to a position where said lens means faces the other of said cover plates so that micro reproductions located on either side of said center plate may be read through said lens means.

6. A reading device for reading micro reproductions comprising, in combination, a plate assembly having a center plate and a pair of cover plates respectively extending over opposite surfaces of said center plate, at least said cover plates being made from transparent material, Vsaid plate assembly adapted to carry micro reproductions sandwiched between said center plate and said cover plates; elongated clamping means for clamping said plates together and extending along at least one edge portion of said plate assembly; guide means extending longitudinally along said clamping means; a U-shaped track member having a pair of leg portions respectively extending along the outer surfaces of said cover plates and substantially normal` to said one edge portion between said one edge portionl and the other edge portion of said plate assembly, said track member having a connecting portion connecting said leg portions and straddling said other edge portion of said plate assembly, said track member being movably connected at the free ends movement over said plate assembly; a lens carrier slidably mounted on said U-shaped track member for sliding movement along said leg portions and said connecting portions thereof; and lens means mounted on said lens carrier and facing one of said cover plates, whereby said lens carrier and said lens means mounted thereon may be moved along said U-shaped track member from a position where said lens means faces said one cover plate to a position where said lens means faces the other of said cover plates so that micro reproductions located on either side of said center plate may be read through said lens means.

7. A reading device for reading micro reproductions comprising, in combination, a circular plate assembly having a circular center plate and a pair of circular cover plates respectively extending over opposite surfaces of said center plate, each of said plates ybeing formed with a central hole, at least said cover plates being made from transparent material, said plate assembly adapted to carry micro reproductions sandwiched between said center plate and said cover plates; a pivot pin mounted in said central holes of said plates and extending therethrough and having opposite end portions projecting respectively beyond the outer surfaces of said cover plates; a U-shaped track member having a pair of leg portions respectively extending along the outer surfaces of said cover plates, said track member having a connecting portion connecting said leg portions and straddling the'circumferential edge portion of said plate assembly, said track member being movably connected at the free ends of said leg portion thereof to said opposite end portions of said pivot pin, respectively, for movement over said plate assembly; a lens carrier slidably mounted on said U-shaped track member for sliding movement along said leg portions and said connecting portions thereof; and lens'means mounted on said lens carrier and facingtone of saidlcover plates, whereby said lens carrier and said lens means mounted thereon may be moved along said U-shaped track member from a position where said lens means faces said one cover plate to a position Where said lens means faces the other of said cover plates so that micro reproductions located .on eitherside of said center plate may be read through said lens means. n

8.A reading device for readmg micro reproductions comprising, in combination, a plate assembly: havingi a center plate and a pair of cover platesrespectively'extending over opposite surfaces of said center plate, at least said cover plates being made from transparent material, said plate assembly adapted to` carry micro Vreproductions sandwiched between said center plate and said cover plates; clamping means for clamping said plates together; elongated track-means having a pair ofguide l portions and a pair of connecting `portions connectingsaid guide portions and straddlingeopposite edge portions of saidplate assembly, said elongated drive means being formed by apairA of elongatedmembers formed from resilient material, said track means mounted on-said clamping means for movement of said guide portions substantially parallel to and over-the outer planar surfaces of said cover plates, repsectively; a lens carrier slidably mo-unted on said elongated track means for slidingmovement along said guide portions and said connecting portions thereof: and lens means mounted onV said lens carrier and facing one of said cover plates,

whereby said lens carrier and said lens means mounted' thereon may be moved along said track means from a position where said lens means faces said one cover plate 4toa position where said lens means-faces the-other4 of said cover plates so that micro reproductions located oneither side of said center plate may be read through said lens means.

9. A reading device for reading micro reproductions comprising, in combination, a plate assembly having a center plate and a pair of cover plates respectively eX- tending over opposite surfaces of said center plate, atleast said cover plates being made from transparent ma-` terial, said plate assembly adapted to carry micro reproductions sandwiched between said center plate andsaid cover plates; clamping means for clamping said plates together; elongated track means havinga pair of guide portions and atleast oneconuecting portion" connecting said guide portions, said track means being-- formed from magnetic material, said track' means movably mounted on said clamping means for movement of said guide portions substantially parallel to and overl the outer planar surfaces of said cover plates, respectively,v

rier and facing one of said cover plates, whereby said lens carrier and said lens means mounted thereon may. be .moved along said track means from a position where' said lens means faces said one cover plate to a positionV where said lens means faces the other of said cover plates so that micro reproductions located on either side of said center plate may be read through said lens means.

l0. A reading device for reading micro reproductions comprising, in combination, a plate assembly havingia:

center plate and a pair of cover plates respectivelyextending over opposite surfaces of said center plate, at least said cover plates being made from transparent' material, said plate assembly adapted to carry micro repro-V ductions sandwiched between said center plate and said:A coverA plates; elongated 'clamping means for clamping said platestogether and extending along at least one edge portionof said plate assembly; guide means extendinglongitudinally along said clamping means; a U-shaped track" 12 member having la pair of legportions respectivelyextending along Athe outer surfaces of said cover plates andl substantially normal to said one edge portion between said one edge portion and the other edge portion of said v plate-assembly, said track member having ,a connecting portion connecting said leg portions and straddling said s other-edgeportion of Vsaid plate assembly, said 4track memberibein'g movably connected at the free endsof said leg portions thereof to' said guide means for 'movementf over said plate assembly; aV lens carrier slidably mounted on said U-shaped-track-member for sliding movement along said leg portions and said connecting portions thereof; and lens means mounted on said lens carrier and. facing'one of said cover plates, said lens means comprisingzareading lens and afview nding lens mounted forturning about the axis of said reading lens, wherebyy said lens-carrier and said lens means mounted thereon` maybelmoved alongf-said U-shaped track member :fromaposition whereV said lens means' faces said one cover plate r to a position where said lens means faces theother of said cover plates so that micro reproductions located on either 'side of said center plate may be read through-said lens means.

11. A` readingdevice for vreading micro reproductions comprising, -in' combinationay plate assembly havingva.' centerL plate and apair of' cover plates respectively eX- tending over opposite surfaces of said center' plate, said` plates of said plate assembly being made from ytransparent,E material, said plate assembly adapted to carry'microref` productionsysandwiched between said center platel `and said cover plates; elongated'clamping means 'forclamp-t ing-said plates together and extending, along at least Vone edge portion of said plate assembly; guide means extend inglongitudinally along said clamping means; a rU-shap'ed-r track'me'mber having apair'of leg portions-respectively:

extendingralongrthe -outer surfaces of saidY cover-plates` and vsubstantially,normal to said one edge portionbe-` tween'said one edgefportion and the other edge portions of said plate assembly,,said track member havingaconz nectingnportion connectingisaidfleg portions and'rstradef dling said other edge portion of said plate assemblygsaidf trackfmember being movably connected at the free-ends'-r of said leg portions thereof to said guide means -for movement over said plate assembly; a lens carrier slidably; mounted on said U-shaped track member for sliding move-'- ment along said legrportions and said connecting portions thereofjand lens means comprising a reading lensfmount-- ed on said lens carrier and facing one of said cover plates, v and acondenser` lenslocated opposite said reading lens and facing the other of said cover plates, said condenser lens being operatively connected to said reading lens'for simultaneous movement therewith, whereby said lens carrier and said lens means mounted thereon may be moved-' along said U-shaped track member from a positionwherei: said lens means faces said one cover platetoa position? where said lens means faces the other of said cover plates? so that 'microreproductions locatedon either side of--said center plate may be readthrough said lens means.

References Cited in the le of this patent UNITED STATES PATENTS 7,961 NystromV Mar. 4, 1851sV 443,359 Duncan Dec. 23,l 1890 533,324 Stevens Jan; 29; 1895i 540,184 Norris May 28, 1895 1,007,760 Williamsl Nov. 7,19l1` 2,127,711 Baldauf Aug.` V23, 1938' 2,166,988 Fosdick July 25, 1939? 2,533,628 Rosenberg Dect-12, 19505y 2,556,806 Gaire JunelZ, 1951* 

